U.S. patent application number 12/410873 was filed with the patent office on 2009-10-01 for electrostatic chuck and manufacturing method thereof.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Tsuyoshi HIDA, Takashi Yamamoto.
Application Number | 20090243236 12/410873 |
Document ID | / |
Family ID | 41115938 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090243236 |
Kind Code |
A1 |
HIDA; Tsuyoshi ; et
al. |
October 1, 2009 |
ELECTROSTATIC CHUCK AND MANUFACTURING METHOD THEREOF
Abstract
An electrostatic chuck of a stack structure includes a metal
layer interposed between insulating layers and a groove formed at a
peripheral portion of the electrostatic chuck to have a width
gradually increasing toward an outside, the groove being covered
with a thermally sprayed insulating film. The thermally sprayed
film covers at least a portion of the metal layer exposed at an
inside of the groove such that the thermally sprayed film does not
protrude from the groove.
Inventors: |
HIDA; Tsuyoshi; (Nirasaki
City, JP) ; Yamamoto; Takashi; (Nirasaki City,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOKYO ELECTRON LIMITED
Tokyo
JP
|
Family ID: |
41115938 |
Appl. No.: |
12/410873 |
Filed: |
March 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61055553 |
May 23, 2008 |
|
|
|
Current U.S.
Class: |
279/128 ;
427/453 |
Current CPC
Class: |
H01L 21/6833 20130101;
H01L 21/6831 20130101; H01L 21/67115 20130101; Y10T 29/49986
20150115; Y10T 279/23 20150115 |
Class at
Publication: |
279/128 ;
427/453 |
International
Class: |
H02N 13/00 20060101
H02N013/00; C23C 4/10 20060101 C23C004/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2008 |
JP |
2008-085417 |
Claims
1. An electrostatic chuck of a stack structure comprising: a metal
layer interposed between insulating layers; and a groove formed at
a peripheral portion of the electrostatic chuck to have a width
gradually increasing toward an outside, the groove being covered
with a thermally sprayed insulating film.
2. The electrostatic chuck of claim 1, wherein the thermally
sprayed film covers at least a portion of the metal layer exposed
at an inside of the groove such that the thermally sprayed film
does not protrude from the groove.
3. The electrostatic chuck of claim 1, wherein the metal layer is a
conductive layer or a uniform heating layer.
4. The electrostatic chuck of claim 1, wherein a cross section of
the groove has any one selected from a group consisting of a funnel
shape, a parabolic shape, a shallow dish shape with a flat bottom,
an elliptical arc shape and a circular arc shape.
5. The electrostatic chuck of claim 1, wherein the thermally
sprayed film is a ceramic insulating film containing alumina.
6. The electrostatic chuck of claim 1, wherein the thermally
sprayed film is formed by thermally spraying yttrium oxide.
7. The electrostatic chuck of claim 1, wherein a surface of the
thermally sprayed film is ground.
8. The electrostatic chuck of claim 1, wherein the metal layer has
a width of 1.0 mm or less.
9. A method of manufacturing an electrostatic chuck of a stack
structure including a metal layer interposed between insulating
layers, the method comprising: forming a groove at a peripheral
portion of the electrostatic chuck to have a width gradually
increasing toward an outside; forming a thermally sprayed
insulating film to cover at least a portion of the metal layer
exposed at the groove; and grinding the thermally sprayed film such
that the thermally sprayed film does not protrude from the
groove.
10. The method of claim 9, wherein the metal layer is a conductive
layer or a uniform heating layer.
11. The method of claim 9, wherein a cross section of the groove
has any one selected from a group consisting of a funnel shape, a
parabolic shape, a shallow dish shape with a flat bottom, an
elliptical arc shape and a circular arc shape.
12. The method of claim 9, wherein the thermally sprayed film is
formed by thermally spraying a ceramic material containing
alumina.
13. The method of claim 9, wherein the thermally sprayed film is
formed by thermally spraying yttrium oxide.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an electrostatic chuck used
in a mounting table on which a substrate to be processed, such as a
semiconductor wafer, is mounted; and more particularly, to an
electrostatic chuck including a thermally sprayed ceramic coating
(hereinafter, also referred to as a thermally sprayed layer) and a
manufacturing method thereof.
BACKGROUND OF THE INVENTION
[0002] In a semiconductor processing apparatus that performs plasma
etching on a substrate to be processed, such as a silicon wafer,
the substrate is mounted on a mounting table installed at the
center of a processing chamber. The mounting table generally has a
structure in which an electrostatic chuck (hereinafter, referred to
as an `ESC`) is provided at the top of a support made of a metal
material exhibiting high thermal conductivity.
[0003] Generally, the electrostatic chuck has a stack structure
including an insulating (dielectric) layer disposed at an uppermost
portion of the electrostatic chuck, a film-shaped electrode, which
is a conductive layer and is disposed below the insulating layer,
and an insulating layer disposed below the film-shaped electrode.
The insulating layer is generally made of alumina
(Al.sub.2O.sub.3). An aluminum sheet, an aluminum foil, or an
aluminum joint layer is generally used as the film-shaped
electrode. The film-shaped electrode functions as a voltage
application electrode to hold the wafer with an electrostatic
force.
[0004] Also, in addition to the film-shaped electrode, a heat
transfer layer made of a metal material may be provided at the ESC
to render the temperature of the ESC uniform.
[0005] The film-shaped electrode and the heat transfer layer are
metal layers made of an electrically conductive metal material.
Both the film-shaped electrode and the heat transfer layer are
exposed from a peripheral side surface of the ESC. When the ends of
the metal layers are exposed from the peripheral side surface of
the ESC, the metal layers may be corroded by, for example, a
halogen-based corrosion gas used to manufacture semiconductors.
Also, the corroded metal may cause contamination.
[0006] Also, when the film-shaped electrode is used as an electrode
of the ESC, an electric discharge or an electric leakage to a metal
body adjacent to the film-shaped electrode, e.g., a focus ring
installed at a periphery of the ESC, may occur because a high
voltage is applied to the film-shaped electrode.
[0007] Accordingly, an insulating ceramic material or alumina may
be thermally sprayed on the peripheral side surface of the ESC from
which the metal layers are exposed in order to prevent the
occurrence of the above-mentioned problem.
[0008] For example, Patent Document 1 discloses a susceptor used in
the manufacture of semiconductors and having a conductor and an
insulating ceramic member, the susceptor being characterized in
that a portion of the conductor exposed from the ceramic member is
covered with a thermally sprayed insulating film.
[0009] [Patent Document 1] Japanese Patent Laid-open Application
No. H06-279974
[0010] An electrostatic chuck generally has a stack structure
including a conductive layer and insulating layers between which
the conductive layer is interposed. When the conductive layer is
exposed to the outside, an electric leakage from the conductive
layer may occur, or a metal material of the conductive layer may be
corroded by an atmosphere gas. Accordingly, a thermally sprayed
film made of an insulating material, such as a ceramic material, is
formed at the exposed portion of the conductive layer, i.e., the
peripheral side surface of the electrostatic chuck, to cover the
exposed portion of the metal layer. However, the thermally sprayed
film formed for such purpose may be easily damaged.
[0011] FIGS. 5A to 5C illustrate examples of shapes of a thermally
sprayed ceramic coating (thermally sprayed layer) formed at the
peripheral side surface of an electrostatic chuck in a conventional
technique. Generally, as shown in FIG. 5A, a flat thermally sprayed
ceramic layer 6 is formed almost entirely at the peripheral side
surface of an electrostatic chuck (ESC) 21 including a conductive
layer 20. However, since the thermally sprayed ceramic layer 6 is
soft, the thermally sprayed ceramic layer 6 may be easily damaged
when an external impact is applied to the thermally sprayed ceramic
layer 6 during handling, such as installation or separation, of the
ESC.
[0012] The inventors of the present invention have examined effects
of a thermal spraying method of changing a shape or a covering
range of the thermally sprayed ceramic layer to prevent the
thermally sprayed ceramic layer from being easily peeled off. As
one example, as shown in FIG. 5B, the thermally sprayed ceramic
layer 6 is extended horizontally from the top and bottom of the
thermally sprayed ceramic layer 6 such that the thermally sprayed
ceramic layer 6 is formed at the top and bottom of the upper and
lower insulating layers as well as at the side of the ESC. As
another example, as shown in FIG. 5C, the thermally sprayed ceramic
layer 6 is extended only from the bottom of the thermally sprayed
ceramic layer 6 such that the thermally sprayed ceramic layer 6 is
formed at the bottom of the lower insulating layer as well as at
the side of the ESC. The inventors have examined the effects of
preventing the thermally sprayed ceramic layer from being peeled
off when the thermally sprayed ceramic layer is formed in the
above-mentioned shapes.
[0013] As a result, the peeling is efficiently prevented by
increasing the adhesion area; however, corners of the thermally
sprayed ceramic layer are damaged by an external impact since the
thermally sprayed ceramic layer is thin and soft. Accordingly, it
has been revealed that it is impossible to completely prevent the
damage to the thermally sprayed ceramic layer due to an external
impact although the thermally sprayed ceramic layer is formed in
the shape shown in FIG. 5B or 5C.
[0014] Further, Patent Document 1 discloses a study on a method of
forming the thermally sprayed ceramic film. Hereinafter, the method
of forming the thermally sprayed ceramic film will be described
with reference to FIGS. 6A and 6B. In an embodiment of the cited
patent document, as shown in FIG. 6A, an upper part of the
susceptor has a structure in which a film-shaped electrode 24 is
interposed between a disc-shaped ceramic member 22 and a
disc-shaped ceramic support 23.
[0015] Further, a thermally sprayed film (thermally sprayed layer)
is formed as follows. First, as shown in FIG. 6A, a peripheral
portion of the film-shaped electrode 24 is removed by etching, and
an insulating ceramic material is sprayed into a groove 25 formed
by removing the peripheral portion of the film-shaped electrode 24.
During spraying, a thermally sprayed ceramic layer 6 is formed to
fill the groove 25 and protrude from the sides of the upper and
lower ceramic circular plates.
[0016] As a result, the thermally sprayed ceramic layer 6 filled in
the groove 25 is formed to thereby improve adhesion between the
disc-shaped ceramics and the thermally sprayed ceramic layer 6.
However, the inventors have found that the thermally sprayed
ceramic layer 6 has a protruding portion, which may easily collide
with a surrounding object. It is known that, when the protruding
portion of the thermally sprayed ceramic layer 6 collides with a
surrounding rigid body, an external impact is applied to the
thermally sprayed ceramic layer 6, and the thermally sprayed
ceramic layer 6 is damaged and easily peeled off.
[0017] Further, in an etching process of the peripheral portion of
the film-shaped electrode 24 as disclosed in Patent Document 1, the
ceramic material is not sufficiently inserted into the processed
portion. Accordingly, it is difficult to fully cover the metal
layer. Also, since a contact area between the thermally sprayed
ceramics and the processed portion is not sufficient, an adhesion
strength between the thermally sprayed ceramics and the processed
portion is poor and, thus, the thermally sprayed ceramics may be
easily peeled off from the processed portion.
SUMMARY OF THE INVENTION
[0018] In view of the above, the present invention provides an
electrostatic chuck of a stack structure including an conductive
layer and insulating layers between which the conductive layer is
interposed, wherein the adhesivity between a thermally sprayed
ceramic film formed at a periphery of the electrostatic chuck and
the electrostatic chuck is high, and the thermally sprayed film is
not easily damaged even when an external impact is applied to the
electrostatic chuck during handling of the electrostatic chuck.
[0019] In accordance with a first aspect of the present invention,
there is provided an electrostatic chuck of a stack structure
comprising: a metal layer interposed between insulating layers; and
a groove formed at a peripheral portion of the electrostatic chuck
to have a width gradually increasing toward an outside, the groove
being covered with a thermally sprayed insulating film.
[0020] In the electrostatic chuck, preferably, the thermally
sprayed film covers at least a portion of the metal layer exposed
at an inside of the groove such that the thermally sprayed film
does not protrude from the groove. Accordingly, it is possible to
prevent an electric leakage from the metal layer or corrosion of
the metal layer, and it is also possible to prevent the damage to
the thermally sprayed film even when an external impact is applied
to the thermally sprayed film during handling of the electrostatic
chuck.
[0021] The metal layer may be a conductive layer or a uniform
heating layer. Further, preferably, a cross section of the groove
has any one selected from a group consisting of a funnel shape, a
parabolic shape, a shallow dish shape with a flat bottom, an
elliptical arc shape and a circular arc shape. Accordingly, even
when the metal layer has a small width of about 0.5 mm to about 1.0
mm, a thermally sprayed ceramic is filled in the groove and it is
possible to prevent the thermally sprayed film from being peeled
off.
[0022] Further, preferably, the thermally sprayed film is a ceramic
insulating film containing alumina. Further, preferably, the
thermally sprayed film is formed by thermally spraying yttrium
oxide.
[0023] Further, when the thermally sprayed film protrudes from the
groove by spraying the ceramic material on the groove, the surface
of the thermally sprayed film is ground to remove the protruding
portion from the groove. Accordingly, it is possible to prevent the
thermally sprayed film from being damaged due to an external
impact.
[0024] In the electrostatic chuck, the thermally sprayed film can
be formed even when the metal layer has a width of about 0.5 mm to
about 1.0 mm.
[0025] In accordance with a second aspect of the present invention,
there is provided a method of manufacturing an electrostatic chuck
of a stack structure including a metal layer interposed between
insulating layers, the method comprising: forming a groove at a
peripheral portion of the electrostatic chuck to have a width
gradually increasing toward an outside; forming a thermally sprayed
insulating film to cover at least a portion of the metal layer
exposed at the groove; and grinding the thermally sprayed film such
that the thermally sprayed film does not protrude from the
groove.
[0026] Accordingly, it is possible to prevent an electric leakage
from the metal layer or corrosion of the metal layer, and it is
also possible to manufacture an electrostatic chuck capable of
preventing the damage to the thermally sprayed film even when an
external impact is applied to the thermally sprayed film during
handling of the electrostatic chuck. Further, the metal layer may
be a conductive layer or a uniform heating layer.
[0027] Preferably, a cross section of the groove has any one
selected from a group consisting of a funnel shape, a parabolic
shape, a shallow dish shape with a flat bottom, an elliptical arc
shape and a circular arc shape. Accordingly, even when the metal
layer has a small width of about 0.5 mm to about 1.0 mm, a
thermally sprayed ceramic is filled in the groove and it is
possible to manufacture an electrostatic chuck capable of
preventing the thermally sprayed film from being peeled off.
[0028] Preferably, the thermally sprayed film is formed by
thermally spraying a ceramic material containing alumina. Further,
preferably, the thermally sprayed film is formed by thermally
spraying yttrium oxide.
[0029] In accordance with the aspects of the present invention, it
is possible to provide an electrostatic chuck including a thermally
sprayed ceramic to cover a metal layer, wherein a thermally sprayed
film is not easily damaged even when an external impact is applied
to the electrostatic chuck.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The objects and features of the present invention will
become apparent from the following description of embodiments given
in conjunction with the accompanying drawings, in which:
[0031] FIGS. 1A and 1B illustrate an upper structure of a mounting
table including an electrostatic chuck in accordance with an
embodiment of the present invention;
[0032] FIG. 2 is a cross sectional view showing a cross sectional
shape of a thermally sprayed ceramic layer formed at a peripheral
side surface of the electrostatic chuck in accordance with the
embodiment of the present invention;
[0033] FIGS. 3A to 3D illustrate other examples of cross sectional
shapes of a groove formed at the peripheral side surface of the
electrostatic chuck in accordance with the embodiment of the
present invention;
[0034] FIGS. 4A to 4D illustrate a method of forming the thermally
sprayed ceramic layer in accordance with the embodiment of the
present invention;
[0035] FIGS. 5A to 5C illustrate examples of shapes of a thermally
sprayed ceramic layer formed at the peripheral side surface of an
electrostatic chuck in a conventional technique; and
[0036] FIGS. 6A and 6B are explanatory diagrams illustrating a
conventional method of forming a thermally sprayed ceramic
layer.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] Hereinafter, embodiments of the present invention will be
described in detail with reference to the accompanying drawings
which form a part hereof. FIGS. 1A and 1B illustrate an upper
structure of a mounting table including an electrostatic chuck
(ESC) in accordance with an embodiment of the present invention.
Specifically, FIG. 1A is a vertical cross sectional view of the
mounting table, and FIG. 1B is an enlarged view illustrating a part
A of FIG. 1A. A support 2 is in contact with the semiconductor
wafer 1 to exchange heat with the semiconductor wafer 1, thereby
serving as a heat exchange plate to control the temperature of a
semiconductor wafer 1. The support 2 is made of a material, such as
aluminum, exhibiting high electric conductivity and thermal
conductivity.
[0038] At an uppermost portion of the support 2 is disposed a
disc-shaped electrostatic chuck layer 3. Below the electrostatic
chuck layer 3 is disposed a disc-shaped heater layer 4 made of a
ceramic material. Between the electrostatic chuck layer 3 and the
heater layer 4 is disposed an aluminum joint layer 5.
[0039] The aluminum joint layer 5 functions to render uniform the
temperature of the semiconductor wafer 1. At the outer peripheries
of the electrostatic chuck layer 3, the heater layer 4 and the
aluminum joint layer 5 is formed a thermally sprayed ceramic layer
6.
[0040] The electrostatic chuck layer 3 is made of a dielectric,
such as a ceramic or the like, to hold the semiconductor wafer 1
with an electrostatic adsorptive force. An internal electrode 7,
which is made of a conductor, e.g., a conductive film of copper,
tungsten or the like, is embedded in the electrostatic chuck layer
3. When a high voltage, e.g., a DC voltage of 2500 V or 3000 V, is
applied to the internal electrode 7 via a power feed rod 8, the
semiconductor wafer 1 is adsorptively held by a Coulomb force or a
Johnson-Rahbek force.
[0041] The heater layer 4 has a structure in which a film-shaped
resistance heating layer 9 is formed in a ceramic disc. Power feed
lines 10a and 10b are attached to opposite ends of the resistance
heating layer 9 such that heating power is supplied to the
resistance heating layer 9 from a commercial AC or DC power source
(not shown).
[0042] A heat transfer medium (fluid) channel 11 is formed in the
support 2. A heat transfer medium of a predetermined temperature,
such as hot water or cold water, is circulated through and supplied
to the heat transfer medium channel 11 by using a temperature
control unit and fluid supply and discharge lines (both are not
shown).
[0043] A heat transfer gas, e.g., a He gas, is supplied between the
electrostatic chuck layer 3 and a backside of the semiconductor
wafer 1 from a heat transfer gas supply unit (not shown) via gas
supply lines 12. The heat transfer gas increases thermal
conductivity between the electrostatic chuck layer 3 and the
semiconductor wafer 1.
[0044] In this embodiment, the electrostatic chuck provided with
the heater is employed as described above. The electrostatic chuck
has a stack structure in which two ceramic discs having almost the
same diameter, forming the electrostatic chuck layer 3 and the
heater layer 4, are joined to each other via the aluminum joint
layer 5. In this embodiment, alumina is used as the ceramics for
the electrostatic chuck layer 3 and the heater layer 4, each of
which has a thickness of about 1 to 2 mm. The aluminum joint layer
5 has a thickness of about 0.5 to 1 mm. A total thickness of the
electrostatic chuck is about 3 to 5 mm. The aluminum joint layer 5
functions to render uniform the temperature of the semiconductor
wafer 1 such that the semiconductor wafer 1 is not uniformly heated
by the heater layer 4.
[0045] When forming the thermally sprayed ceramic layer 6 at the
outer periphery of the disc-shaped stack structure, a groove is
formed first such that an outer periphery of the aluminum joint
layer 5 is exposed to the outside. The thermally sprayed ceramic
layer 6 is then filled in the groove. Finally, a height of the
thermally sprayed ceramic layer 6 is adjusted such that the top of
the thermally sprayed ceramic layer 6 does not protrude from the
peripheral side surface of the stack structure.
[0046] Hereinafter, a cross sectional shape of the groove formed at
the peripheral side surface of the stack structure in accordance
with the embodiment of the present invention will be described.
FIG. 2 is a cross sectional view showing a cross sectional shape of
the thermally sprayed ceramic layer 6 formed at the peripheral side
surface of the electrostatic chuck in accordance with the
embodiment of the present invention.
[0047] As shown in FIG. 2, the electrostatic chuck 30 includes the
electrostatic chuck layer 3, the heater layer 4 and the aluminum
joint layer 5 interposed therebetween. A lower peripheral part of
the electrostatic chuck layer 3 and an upper peripheral part of the
heater layer 4 are cut to form flat inclined surfaces, thereby
forming a groove along the entire peripheral side surface of the
electrostatic chuck 30. The groove is formed such that the aluminum
joint layer 5 is exposed at the bottom of the groove.
[0048] The cross section of the groove may have a shallow funnel
shape or a shallow dish shape with a flat bottom. A ceramic
spraying material is thermally sprayed such that the thermally
sprayed ceramic layer 6 entirely covers the groove. Preferably,
yttrium oxide or alumina may be used as the spraying material, but
the spraying material is not limited thereto as long as the
spraying material forms a ceramic. After spraying, the spraying
material protrudes outside the groove. Accordingly, the protruding
portion of the spraying material is ground to adjust the height of
the thermally sprayed ceramic layer 6 such that the top of the
thermally sprayed ceramic layer 6 does not protrude from the
peripheral side surface of the stack structure. In other words, the
portion of the thermally sprayed ceramic layer 6 sticking out of
the groove is removed to render the exposed surface of the
thermally sprayed ceramic layer 6 to be flush with the outer
peripheral side surfaces of the electrostatic chuck layer 3 and the
heater layer 4.
[0049] The present invention has the following two features to
enhance adhesivity between the thermally sprayed ceramic layer 6
and the ESC. As for a first feature, referring to FIG. 2, the
groove is formed to have a cross section in which a width of the
groove is gradually widened toward the outside (i.e., an outside
width (D1) of the groove>an inside width (D2) of the groove), so
that a liquid spaying material can easily reach the bottom (the
inside) of the groove during spraying. As for a second feature, as
will be described later, the groove is formed such that a total
length (L) of the bottom and side walls thereof in the vertical
cross section of the groove shown in FIG. 2 is 1.42 mm or more,
thereby increasing an adhesion area between the thermally sprayed
ceramic layer 6 and the electrostatic chuck 30.
[0050] As for the first feature, the cross sectional shape of the
groove is not limited to the example of FIG. 2. FIGS. 3A to 3D
illustrate other examples of the cross sectional shapes of the
groove in accordance with the embodiment of the present invention.
As shown in FIG. 3A, the cross section of a groove 13 may have a
funnel shape. As shown in FIG. 3B, the cross section of the groove
13 may have a shallow dish shape with a flat bottom. Further, as
shown in FIG. 3C, the bottom corner of the funnel may be rounded
with a predetermined radius of curvature R. As shown in FIG. 3D,
the cross section of the groove 13 may have a circular arc shape.
Alternatively, although not shown, the cross section of the groove
13 may have an elliptical arc shape or a parabolic shape. When the
cross section of the groove 13 includes a curved shape, the bottom
of the groove 13 including the exposed portion of the aluminum
joint layer 5 may be flat.
[0051] Further, as for the second feature, preferably, the total
length (L) of the bottom and side walls of the groove is about 1.42
mm in the cross section of the groove, thereby improving adhesivity
of the thermally sprayed ceramic layer 6 to the electrostatic chuck
layer 3 and the heater layer 4. Therefore, it is possible to
efficiently prevent the thermally sprayed ceramic layer 6 from
being peeled off.
[0052] Further, the height of the thermally sprayed ceramic layer 6
is adjusted by removing the protruding portion of the thermally
sprayed ceramic layer 6 such that the thermally sprayed ceramic
layer 6 does not protrude from the peripheral side surface of the
stack structure. Consequently, it is possible to prevent the
thermally sprayed ceramic layer 6 from being damaged due to the
collision between the protruding portion of the thermally sprayed
ceramic layer 6 and a surrounding rigid body during handling. The
protruding portion of the thermally sprayed ceramic layer 6 may be
removed by conventional machining; however, a method of removing
the protruding portion of the thermally sprayed ceramic layer 6 is
not particularly restricted.
[0053] A method of manufacturing the electrostatic chuck, i.e., a
method of forming the thermally sprayed ceramic layer 6, in
accordance with the embodiment of the present invention, will be
described. FIGS. 4A to 4D illustrate a method of forming the
thermally sprayed ceramic layer 6 in accordance with the embodiment
of the present invention. First, as shown in FIG. 4A, two ceramic
discs of the electrostatic chuck layer 3 and the heater layer 4 are
joined to each other via the aluminum joint layer 5 to construct a
stack structure 14. Subsequently, as shown in FIG. 4B, an outer
periphery of the stack structure 14 is ground to form the groove 13
having a specific cross section.
[0054] Subsequently, as shown in FIG. 4C, a ceramic spraying
material is thermally sprayed to entirely fill the groove 13 at the
outer periphery of the stack structure 14 while slightly protruding
outward, thereby forming the thermally sprayed ceramic layer 6. In
this embodiment, yttrium oxide powder or alumina powder is used as
the spraying material. After the thermally sprayed ceramic layer 6
is cooled and solidified, the height of the thermally sprayed
ceramic layer 6 is adjusted, such that the top of the thermally
sprayed ceramic layer 6 does not protrude from the peripheral side
surface of the stack structure 14, by mechanically grinding or
polishing the surface of the thermally sprayed ceramic layer 6. As
a result, the thermally sprayed ceramic layer 6 is completely
formed.
[0055] While the invention has been shown and described with
respect to the embodiments, it will be understood by those skilled
in the art that various changes and modifications may be made
without departing from the scope of the invention as defined in the
following claims.
* * * * *